Xenon is an inert noble gas, and for years everyone assumed it was impossible to form compounds out of it. Then someone who didn't know any better started synthesizing a variety of xenon-fluorine compounds, some of which are actually solids at room temperature. This is quite remarkable.

As a gas xenon is widely used in photographic flash tubes (the electronically triggered kind that can be used many times, not the old one-time chemical flash bulbs). Strobe lights in dance clubs and airplane wings are also xenon tubes.

Flash tube.
Purchased at Radio Shack May 2002. These kinds of tubes are used for photographic flashes.Source:Radio ShackContributor:Theodore GrayAcquired:10 May, 2002Price: $5Size: 1.5"Purity: >95%

Antique reagent flask.
I got a set of five different noble gas flasks on eBay for $13.50, which seemed like a good deal even though the seller described them as "probably empty". I very much doubt, however, that they are empty: At the bottom where the flask meets the tube, there is a tiny inner breakaway seal that is completely intact on all five of them. There's no visible way for the gas to have escaped. I've learned that one normally uses a steel ball, held up with a magnet, to break the seal: When you've hooked up and flushed out all the connecting tubes, you pull away the magnet and the ball drops onto the seal, breaking it and releasing the gas.
After many unworkable suggestions for proving whether the gases were still in there, several people came up with the idea of using a high voltage transformer, such as one finds in those now inexpensive plasma ball novelty lights, to try to set up an arc inside the flask, and identify the gas from the color of the discharge. Whether this is possible is sensitive to the pressure of the gas, which is not known.
Fortunately, it worked beautifully on three out of the five, and proved beyond a reasonable doubt that those three at least contain the gas claimed. The others almost certainly failed because the type and pressure of gas in them does not support an arc, not because they are empty. In fact, if they were empty, I would have gotten an arc, because the arc works through up to about half an inch of ordinary air.
You can see pictures of all the arcs along with a picture of the display stand I built for them (between 10PM and midnight of the evening they arrived) a using some of the same Carlson Maple used for the noble gas tiles on the table.
By the way, isn't it a cute oxymoron: Reagent-grade non-reactive gas.Source:eBay seller tictoxxContributor:Theodore GrayAcquired:28 August, 2002Text Updated:29 January, 2009Price: $3Size: 9"Purity: 99.95%

Mounted arc tube.
In some ways, gases are a pain from a sample point of view. With the exception of chlorine and bromine they all look exactly the same: Like nothing at all. My beautiful set of noble gas flasks is beautiful because of the flasks, not what's in them, which is indistinguishable from plain air or vacuum. (So much so that I got them for a bargain price because the seller thought the were empty.)

But set up an electric current through almost any gas, and things are completely different. The current ionizes the gas, and when the electrons fall back into their orbits, they emit light of very specific frequencies. These spectral lines can easily be seen with even a very cheap pocket spectroscope, and they give the glowing tubes very unusual colors. So unusual in fact that they are basically impossible to photograph. The pictures here simply don't look at all like the real colors of these tubes, which cannot be represented by the limited red, green, and blue mixtures available in computer or printed photographs.

David Franco helped arrange these tubes, which were made by a guy who specializes in noble gas tubes and Geissler tubes (click the source link). I have tubes installed in each of the five stable noble gas spots in the table, hooked up underneath to a high voltage transformer. They are really quite beautiful. On my Noble Rack page I have all the pictures collected, along with pictures of arcs I made in my other collection of noble gas flasks.

Sample from the RGB Set.
The Red Green and Blue company in England sells a very nice element collection in several versions. Max Whitby, the director of the company, very kindly donated a complete set to the periodic table table.

Sample from the Everest Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (except gases) weigh about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.

Museum-grade sample.
In early 2004 Max Whitby and I started selling individual element samples identical or similar to the samples we use in the museum displays we build. These are top-quality samples presented in attractive forms appropriate to the particular element. They are for sale from Max's website and also on eBay where you will find an ever-changing selection of samples (click the link to see the current listings).

This is a lovely hand-made discharge tube, powered by a small high-voltage transformer. The color is characteristic of the noble gas contained in the tube, and of course the shape spells the element's atomic symbol. In our large periodic table displays we use larger versions of these tubes: The ones photographed here are about 3" tall, but the other ones look basically identical, just bigger.

I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.

Pressurized ampule.
This is a small (1/8" inside diameter) vial of liquid xenon. It takes quite a lot of pressure to turn xenon gas into a liquid, so the vial is made of high-strength quartz glass, and it's embedded in a large cylinder of acrylic to contain the gas if the glass were to break. Hopefully the acrylic would be strong enough.
Actually there is only liquid in the ampule below 16C (61F), so at room temperature it's just gas. Fortunately it's winter now so I could easily cool my studio down to about 50F to photograph the 360 degree rotation I make of every new sample. This process takes half an hour (360 frames shot one every 5 seconds as the sample makes one complete revolution in 30 minutes). I put the sample in the freezer for a few hours, which got it about half full of liquid. You can see it evaporating slowly until only about a fifth of the ampule is liquid by the end of the rotation. (The rotation is shot very close up so all you see is the bit of liquid at the bottom of the vial.)Source:Ivan TimokhinContributor:Ivan TimokhinAcquired:28 December, 2006Text Updated:7 January, 2007Price: DonatedSize: 0.5"Purity: 99%

Xenon short-arc lamp.
Lamps like this are what replaced carbon arc lights in many applications where no other technology would do. Both types of lamp produce light with a small, extremely intense electric arc. Unlike most other kinds of lamps, the light all comes from one very small spot, and there's a huge amount of it. This makes these bulbs suitable for use in search lights and movie projectors where the light needs to be focused into a strong beam: By putting a small source of light at the focal point of a parabolic reflector, you get a beam.
The main advantage of a xenon short arc lamp is that the spark is completely contained in the bulb, which is filled with a fairly high pressure of xenon gas (high enough that larger versions can be quite dangerous and are always handled with a protective case to guard against flying glass). Carbon arc lights operate in the open air, creating smoke and slowly consuming the electrode: They are not completely gone yet, but are pretty much relegated to the point of historical curiosity at this point.Source:eBay seller cieinternationalContributor:Theodore GrayAcquired:8 December, 2007Text Updated:8 December, 2007Price: $12.50Size: 4"Purity: 99%

High power xenon studio flash.
This is a high-power xenon flash tube of the type that I use regularly for photo shoots for my Popular Science column. They are the most common type used in professional studio flashes.Source:Theodore GrayContributor:Theodore GrayAcquired:11 March, 2009Text Updated:12 March, 2009Price: DonatedSize: 4"Purity: <5%

Xenon discharge headlamp.
This is one of those really annoying dazzling headlights you see on cars more expensive than yours. Unlike many you find on eBay it is an actual xenon arc discharge lamp, not a common xenon gas-filled incandescent bulb that many sellers misrepresent as being of this much more expensive type.Source:eBay seller tjauto04Contributor:Theodore GrayAcquired:11 March, 2009Text Updated:12 March, 2009Price: $25Size: 3"Purity: <10%

Xenon short arc lamp and housing.
This is a xenon short-arc tube mounted in its reflective housing. This must be one heck of a bright spot light! There are air vents that make it look like forced air cooling is required. See six samples back for an example of just the arc tube outside of its housing.Source:eBay seller swliquidatorsContributor:Theodore GrayAcquired:24 March, 2009Text Updated:24 March, 2009Price: $15Size: 6"Purity: 99%

Xenon incandescent headlamp.
eBay is full of "xenon headlamps" promoted as if they were the very expensive xenon short-arc headlamps popular in very expensive brands of car and unpopular with everyone else because they cause a lot of glare. But these inexpensive "xenon" lamps are just ordinary incandescent bulbs that are, possibly, filled with xenon gas (which is legitimately used for this purpose, it's just not the same thing as an arc discharge lamp).
These type of fake arc lamp is often wrapped in blue film to make the yellow incandescent light look more like the bright blue/white light from a true arc light.Source:eBay seller bulbsgalore100Contributor:Theodore GrayAcquired:17 April, 2009Text Updated:17 April, 2009Price: $13Size: 2"Purity: <5%